Introduction to Nanopesticides: -
Without
harming the biodiversity in the area, nanotechnology has provided excellent
alternatives for insect pest management in agriculture, allowing for a more
harmonious environment.
Nanopesticides are nanostructures
used to transport agricultural components that have two to three dimensions and
range in size from 1 to 200 nm. When opposed to free insecticides, the loading
of agrochemical ingredients into nanoparticles offers advantages due to their
special features. However, a new category of environmental trash is being
generated due to the rapid development of novel designed nanoparticles for pest
management. Innovative nanopesticides are nanoparticles created to protect
plants, minimize application losses, improve stability, boost leaf coverage,
and decrease the amounts of formulation components. Formulations for
nanopesticides can be split into active encapsulating components such nano
emulsion, polymeric nanoparticles, lipide nanoparticles, and nanotubes, as well
as self-organized systems like liposome, dendrimers, metallic and bimetallic
nanoparticles.
Production has also
been negatively impacted by the indiscriminate use of pesticides applied against
harmful insects and pests. This has led to increased environmental imbalance,
disease and insect resistance. This increased need for new agrochemicals to
ensure the protection of the crops from various pests (pathogens, harmful
insects, parasitic weeds) thus increasing production and productivity.
Disadvantages of conversational pesticides: -
Pesticides
are considered one of the important components of crop protection measures
and have been used widely in agriculture. Their use during the green
revolution era contributed significantly towards increasing the crop
yields besides the use of high-yielding crop varieties alone.
The
book “Silent Spring” published by Rachel Carson in early 1960s drew our
attention to the environmental risks associated with their use. Pesticide overuse causes off-target
waste accumulation and poor targeted delivery, both of which lead to pesticide
resistance and mutations in the target pest's genetic makeup. Pesticide drift
results in the loss of the majority of pesticides, posing environmental risks.
The environment either hydrolyzes or biodegrades the active ingredients
released by pesticide formulations. By leaching, they can even contaminate the
surrounding area.
Various
researches have shown that only 0.1% of the pesticides applied (spray, soil,
seed treatment, etc.) reach the target, while the remaining 99.9%
leaks into the surrounding environment leading to soil and groundwater
pollution, which ultimately hampers the ecological imbalance.
Benefits of Nano pesticides: -
To
strike a dynamic balance between agricultural production and environmental
sustainability, nanotechnology most likely offers a novel platform. Numerous
studies have demonstrated that the application of nanopesticides in agriculture
can significantly reduce costs, enhance shelf life, and improve nutritional
value of agricultural products.
They
are designed specifically to increase the solubility of insoluble or poorly
soluble active ingredients and to release the biocide in a controlled and
targeted manner, in contrast to conventional pesticide formulations. As a
result, the application only requires a smaller amount of an active ingredient
per area. Producing costs, non-target effects, and phytotoxicity are all
reduced as a result of the reduced dose. Additionally, it is essential that
controlled-release formulations remain inactive until the active in-gradient is
released.
For e.g.: -Different
nanopesticides like atrazine, that is mostly sprayed on sugarcane and maize
crops, can induce DNA damage by a chemical reaction with adenine and guanine
bases of the DNA.
Experiment on snails: -
The leaves,
fruits, roots, tubers, and seeds of important economic plants and field crops
are frequently damaged by terrestrial snails. They are currently regarded as
Egypt's primary agricultural and economic pest, reducing crop yields. The
conical snail (Cochlicella acuta) is considered one of the most hazard
pests in Egypt. This pest causes damage to infested, grain crops and pastures
by chewing or rasping the plant leaves while the chocolate banded snail, (Massylaea
vermiculata,) which was previously known as “Eobania vermiculata” is
one of the most harmful snails to many vegetables’ fruits and field crops in
many regions in Egypt. This pest species was also recorded in Europe, Japan, the
USA, Australia, and Egypt.
Nano formulations were created from three
conventional pesticide formulations: chlorfenapyr, imidacloprid,
and indoxacarb. Adults of the conical snail, Cochlicella acuta,
and the chocolate banded snail, Massylaea vermiculata, were tested against
the toxicity of these nanoformulations.
Results: -
The findings revealed that the nanoparticle
sizes, which ranged from 220 to 534, were nanosized, and that the loading
capacities of the selected pesticides on polymer were, respectively, 65.3 ± 6.4,
62.8 ± 5.3 and 37.1 ± 0.4%percent
for nanochlorfenapyr, nanoimidacloprid, and nanoindoxacarb. The nanochlorfenapyr
was the most toxic against both the C. acuta and M.
vermiculata followed by nanoindoxacarb and nanoimidacloprid.
Conclusion:
-
These findings confirmed that
the chocolate banded snail (“M. vermiculata”) was less susceptible to
all of the tested pesticides than the corresponding conical snails. The efficiency
of nanochlorfenapyr, nanoindoxacarb and nanoimidacloprid on
conical snails (6.1, 7.7 and 14.9 ppm, respectively) was about one forth
when compared with M. vermiculata (23.1, 31.9 and
60.6 ppm, respectively). The findings also demonstrated that the
nano formulation's effectiveness extended beyond its direct killing of the
tested snails to include its repellent properties.
The lunch box approach: -
The
lunch box approach is mainly inspired from the mechanism of the” fake promises”
and to attract the prey such as, predator spiders providing same sex signals as
of moth to attract them and making of silk wrapped gifts by male spiders in order to mate with the
female spider. Nanopesticides should, ideally, kill a target without harming
other species or organisms by luring it. By combining a semio-chemical with a
nano-delivery system, the nano lunch-box strategy eliminates the described
randomness of encountering the pesticide.
Here, we present
such an approach, called the “lunch-box” or “deadly-goodies” approach.
It consists of three main
steps:-
(1) the lure,
(2) the box and
(3) the kill.
The aim is to make the pest organism wish to
approach the encapsulated pesticide, i.e., using the attract-to-kill approach
at the nanoscale.
The lure: -
The lunch-box method requires that the pest
organism be seduced into this "belief" that it perceives an advantage
in locating or being close to the "lunch”. According to studies pheromones
can be embedded in nanogels or polymer fibers by anchoring highly appealing
chemicals on the surface of a nanocarrier. Semiochemicals, are the volatile
compounds that indicate attraction and mating, food, or more broadly
host-detecting chemicals, are potential attractants. Even at very low
concentrations, these chemicals can be detected by organisms and induce a
response that overrides many of an organism's natural "fears". These
chemicals can be highly species-specific.
The b0x: -
In this method, if a pest
organism is drawn to the lunchbox, it must "open". The carrier must
be made of something that can be eaten or digested, like cellulose or pectin.
Gut digestive enzymes or physical–chemical factors may initiate the
"opening”. The stability of the carrier, its ability to be opened, and
especially the timing of the box's opening is all dependent on the material
properties. Numerous natural materials can be broken down by enzymes found in
living things, making them suitable for use in nanocarrier systems. As a
result, site-specific pest control could get benefitted from their promotion of
the release of active ingredients. Drug delivery and food science research
served as inspiration for the majority of these site-specific release systems,
whereas agricultural release applications-promoting systems are still in their
infancy. Site-specific nanoparticle-based pesticide delivery methods are very
interesting because they allow for precise effects on an organism while
avoiding ineffective release.
The kill: -
The pesticide can begin working
at the intended location without harming any other organisms once the lunchbox
is opened. The method allows for the use of more gentle and sophisticated
methods in addition to conventional chemicals.
For example, Bt (Bacillus thuringiensis)
can be used against various pest species, within the nanocarriers, novel
natural or biosynthetic “compounds” can also be employed, e.g., natural
chemicals, small-molecule agonists, or novel synthetic RNAi virus like strings.
Conclusion: -
Because the carrier system can
protect and ensure proper functioning, the pesticides are more precise and
generally cause less harm than conventional pesticide chemicals when used with
this system. The “lunchbox” may even be designed to target specific tissues
prior to release because nanocarriers can cross the midgut membrane however,
development of this feature may take longer. It is possible to adjust what can
be contained within the carrier as well as to enhance or inhibit cellular
internalization by controlling the size of the carrier, such as between the nano
and micro sizes.
In conclusion, the lunch-box
concept appears to be extremely promising for the creation of precision
nanopesticides that enable targeted release, increased efficiency, and the
avoidance of widespread pesticide-related negative effects. The interaction
between ecological, nanotechnological, and chemical sciences benefits the
approach.
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